| Code | Effect |
| Crosshair 1 | Gives you crosshairs |
| Fly | Flying mode (D=up C=down) |
| Fov X | Increases peripheral vision (where x is your field of vision) |
| Give #x | gives weapon #x - 3=shotgun, 4=nailgun, etc.. |
| Give C #x | Gives x # cells |
| Give H #x | Gives x # health |
| Give N #x | Gives x # of nails |
| Give S #x | Gives you x # of shells |
| Give R #x | Gives you x # of rockets |
| God | god mode |
| Impulse 9 | All Ite+ms |
| Impulse 10 | Pentagram of Protection |
| Impulse 11 | Rune |
| Impulse 12 | Limited Gimme |
| Impulse 13 | Silver Key |
| Impulse 14 | Gold Key |
| Impulse 252 | Pentagram of Protection (30 seconds) |
| Impulse 253 | Ring of Shadows (30 seconds) |
| Impulse 254 | Bio-suit (30 seconds) |
| Impulse 255 | Quad Damage mode |
| Kill | commit suicide (?) |
| map e#m# | level warp |
| Map End | Takes you to last level |
| _Noclip | walk through walls |
| Notarget | Invisible to enemies |
| R_Fullbright 1 | Everything is bright |
| sv_gravity ### | sets gravity to ### |
| version | Gives you version information |
But wait - There's more!!
Nightmare Skill
Start in Normal skill mode. Go into the 4th episode but don't get into the time portal. When you fall out of the water, go to the console and type in "Fly". Go up , turn left, and enter the doorway...or...
Step into the water but don't fall through. Swim all the way against the wall on the same side you enter the water (where the shield is in deathmatch). Now fall through and you will land on the rafter. Walk on the rafter right into the Nightmare entrance.
If you have a hard time getting anywhere on the rafters, use the NoClip code and walk through walls until you find it.
To be invisible to your deathmatch buddy but not the monsters, type: R_Drawviewmodel 0.
Thanks to Kasmir Gandalf, Azreal, Ben Ridley, Amanda Bearnik,
Josh Riddell, Chris Psaros, Gwhite, Knut Erik Pedersen, Steven Hagle, Marc Lindenbach,
Nick, Michael G. Clawson, Ben Shotts, Richard Cunningham, and Aaron and James!